1. Field of the Invention
The present invention relates generally to a pad conditioning tool, and more particularly a pad conditioning tool that is made from sapphire material and the sapphire material has a specific orientation and the method of manufacturing the pad conditioning tool.
2. The Prior Arts
Typically, CMP (Chemical Mechanical Polishing) technique is generally applied in the production of a semiconductor, which in fact is a process of smoothing surfaces of silicone wafers or other base material with the combination of chemical and mechanical forces, so that it is named CMP. Before this technique comes into existence, other techniques like etchback, glass reflow, spin coating film are implemented for smoothing the surfaces thereof, but do not bring high effect. The IBM has developed CMP technique in late 1980, which results in extremely and fine planarization of surfaces in the semiconductors, and hence the integrated circuits in a great quantity.
The CMP technique generally includes two parts, namely: (I) Polishing (II) Conditioning. For the first part, a polishing pad is mounted on a platen while a wafer to be polished in mounted a wafer carrier via vacuum means and polishing slurry is introduced between the polishing pad and the wafer in order to smooth the surfaces when the two articles oscillate relative to one another, where the slurry smoothes and etches the surfaces by removing the protruded grains from the surfaces, thereby achieving the extremely flat surfaces. For conditioning, several thousands of sapphire grains are implanted in a pad conditioning tool, when the pad conditioning tool rotates on its axis or when two articles oscillates relative to each other so as to remove abrasive waste from the polishing pad and to ensure formation of fine trenches in the surface of the polishing pad. The conditioning process includes (i) in-situ part and (II) ex-situ part. In the in-situ part, polishing and conditioning of the pad surface is done simultaneously and maintains a certain polishing effect without the need of stopping the operation. Presently, CMP technique is applied while the pad conditioning tool removes the protruded grains and the scratches so that the external surface of the polishing pad is formed with new abrasive clearances to absorb the newly introduced slurry, thereby establishing new celia and removal-enhancing material. In the ex-situ part, the conditioning process on the polishing pad is conducted only after finishing the polishing process of the surfaces.
In order for the polishing pad to possess stability of CMP performance, a diamond conditioning tool is implemented so as to maintain the outer surface of the polishing with trenches so as to facilitate removal of by products (waste) therefrom. Referring to FIGS. 1A-2A, which illustrate a prior art pad conditioning tool, includes a plurality of diamond grains B formed on a metal substrate A via sintering or adhesive method. Because the diamond grains B protrude outwardly from the outer surface at different heights, the exterior appearance and dimension is not uniform so that the diamond conditioning tool can only provide roughly about 10% polishing effect. Note that thousands of diamond grains B are electroplated or via brazing sintering process onto the metal substrate A so that there exist co-relation between the surface areas and the number of diamond grains B mounted within the surface area and the diamond grains B at the adjoining surfaces may fall off owing to contraction and expansion of the metal substrate at different temperatures. Another way for mounting the diamond polishing grains B is that an adhesion layer C is firstly coated on the metal substrate A, and the diamond grains B are implanted on the adhesion layer C. The diamond grains B may fall off the adhesion layer C upon introduction of the slurry and the etching process on the adhesion layer C, which, in turn, may result in scratches partially or wholly on the wafer being polished.
Taiwan Patent No. 1264345 discloses a CMP (Chemical Mechanical Polishing) pad conditioning tool, which has strong binding effects for the polishing grains. The pad conditioning tool includes a resin layer, a plurality of super polishing grains implanted securely on the resin layer, the super polishing grains are exposed from the resin layer and an electroplated metal layer between the resin layer and the super polishing grains, wherein a certain of the super polishing grains are exposed to an exterior of the electroplated metal layer. Comparing with those without the electroplated metal layer, the electroplated metal layer provides enhanced adhesion of the super polishing grains relative to the resin layer. However, this patent cannot eliminate the problem of the polishing slurry etching the resin layer, thereby leading to easily falling off the super polishing grains from the pad conditioning tool.
Taiwan Patent No. 1289093 discloses a method of manufacturing a diamond disc. The method accordingly includes the steps of: preparing a container; forming an adhesion layer within the container; covering the adhesion layer with a hollow member having a plurality of meshes; providing a plurality of diamond grains in the meshes of the hollow member in such a manner that the diamond grains are bond on the adhesion layer; afterward, a resin material is introduced into the container such that the diamond grains are implanted securely on the resin material. Finally, the resin material together with the diamond grains is removed from the container so as to achieve the diamond disc, in which the diamond grains are distributed uniformly and in which the diamond grains has the same orientation. This method though cures some problems, but when the resin material comes into contact with the polishing slurry, the reaction causes an etching process that may cause the diamond grains to fall off, which, in turn, may result in scratches partially or wholly on the article (like wafer) which has been polished.
Of late, another pad conditioning tool has been developed, which includes an integrally formed polishing pad made from ceramic material and which can avoid the problem of falling off the diamond grains. However, the total rigidity or hardness of the polishing pad is relatively smaller than that of the diamond grains and still suffers being etched phenomenon when coming into contact with the polishing slurry.
Therefore, how to develop a pad conditioning tool, which does not suffers the disadvantages, like the diamond grains falling off the metal substrate owing to expansion and contraction of the metal substrate at different temperatures, etching of the adhesion layer in coming contact with the polishing slurry, resulting of scratches on the surface of the article (like wafer) which has been polished, the pad conditioning tool serving a longer service life and providing high yield of the finished products.